Ceramic electronic component comprising dielectric grains having a core-dual shell structure and method of manufacturing the same

ABSTRACT

A ceramic electronic component includes a body, including a dielectric layer and an internal electrode. The dielectric layer includes a plurality of dielectric grains, and at least one of the plurality of dielectric grains has a core-dual shell structure having a core and a dual shell. The dual shell includes a first shell, surrounding at least a portion of the core, and a second shell, surrounding at least a portion of the first shell. The dual shell includes different types of rare earth elements R1 and R2, and R2 S1 /R1 S1  is 0.01 or less and R2 S2 /R1 S1  is 0.5 to 3.0, where R1 S1  and R1 S2  denote concentrations of R1 included in the first shell and the second shell, respectively, and R2 S1  and R2 S2  denote concentrations of R2 included in the first shell and the second shell, respectively.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is the continuation application of U.S. patentapplication Ser. No. 17/085,309 filed on Oct. 30, 2020, which claims thebenefit under 35 USC 119(a) of Korean Patent Application No.10-2020-0014955 filed on Feb. 7, 2020 in the Korean IntellectualProperty Office, the entire disclosure of which is incorporated hereinby reference for all purposes.

BACKGROUND 1. Field

The present disclosure relates to a ceramic electronic component and amethod of manufacturing the same.

2. Description of Related Art

In general, a ceramic electronic component using a ceramic material suchas a capacitor, an inductor, a piezoelectric element, a varistor, athermistor, or the like may include a ceramic body formed of the ceramicmaterial, an internal electrode disposed in the ceramic body, and anexternal electrode disposed on a surface of the ceramic body to beconnected to the internal electrode.

Multilayer ceramic capacitors (MLCCs), a type of ceramic electroniccomponent, are being developed to have increasing capacitance throughthe ultra-thinning of layers thereof.

A high-capacitance multilayer ceramic capacitor (MLCC) may includebarium titanate (BaTiO₃) as a main material to form a body, and nickelas a base material of the internal electrode.

Such a body is generally sintered in a reduction atmosphere. In thiscase, the dielectric therein should be resistant to the reduction.

However, due to the inherent characteristics of the oxide, oxygen in theoxide may escape during the sintering operation in the reductionatmosphere to generate oxygen vacancies and electrons. Therefore,reliability and insulation resistance (IR) thereof may be deteriorated.

To address the above issue, a method has been proposed in which a rareearth element such as Dy, Y, Ho, or the like is added to suppress thegeneration of the oxygen vacancies, to reduce mobility of oxygenvacancies, and to remove electrons generated by the addition of atransition metal.

However, there remains an issue that the above method may be noteffective when layers in the multilayer ceramic capacitor are thinned tohave a relatively high capacitance or when a relatively high voltage isused therein under more severe use environments.

In addition, when the rare earth element or the transition element isadded in the above method, high-temperature lifespan characteristics maybe deteriorated or a temperature coefficient of capacitance (TCC)characteristic, depending on a change in temperature, may bedeteriorated.

SUMMARY

An aspect of the present disclosure is to provide a ceramic electroniccomponent and a method of manufacturing the same, capable of improvingreliability.

An aspect of the present disclosure is to provide a ceramic electroniccomponent and a method of manufacturing the same, capable of improvinghigh-temperature lifespan characteristics.

An aspect of the present disclosure is to provide a ceramic electroniccomponent and a method of manufacturing the same, capable of improvingtemperature coefficient of capacitance (TCC) characteristics.

However, the objects of the present disclosure are not limited to theabove description, and will be more easily understood in the process ofdescribing specific embodiments of the present disclosure.

According to an aspect of the present disclosure, a ceramic electroniccomponent includes a body, including a dielectric layer and an internalelectrode, and an external electrode disposed on the body and connectedto the internal electrode. The dielectric layer includes a plurality ofdielectric grains, and at least one of the plurality of dielectricgrains has a core-dual shell structure having a core and a dual shell.The dual shell includes a first shell, surrounding at least a portion ofthe core, and a second shell, surrounding at least a portion of thefirst shell. The dual shell includes two different types of rare earthelements R1 and R2, and R2_(S1)/R1_(S1) is 0.01 or less andR2_(S2)/R1_(S1) is 0.5 to 3.0, where R1_(S1) and R1_(S2) denoteconcentrations of R1 included in the first shell and the second shell,respectively, and R2_(S1) and R2_(S2) denote concentrations of R2included in the first shell and the second shell, respectively.

According to an aspect of the present disclosure, a method ofmanufacturing a ceramic electronic component having a core-dual shellstructure having a core and a dual shell in the dielectric layerincludes preparing a base material powder having a core-shell structurehaving a core and a shell, wherein the shell includes a rare earthelement R1, adding a minor component including a rare earth element R2,which is different from the rare earth element R1, to the base materialpowder to prepare a ceramic green sheet, printing a conductive paste foran internal electrode on the ceramic green sheet, and then laminatingthe printed ceramic green sheet to prepare a laminate, sintering thelaminate to prepare a body including a dielectric layer and an internalelectrode, and forming an external electrode on the body. A content ofR2 is 0.1 to 3.0 times a content of R1.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will be more clearly understood from the following detaileddescription, taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic perspective view illustrating a ceramic electroniccomponent according to an embodiment of the present disclosure.

FIG. 2 is a schematic cross-sectional view taken along line I-I′ in FIG.1 .

FIG. 3 is a schematic cross-sectional view taken along line II-II′ ofFIG. 1 .

FIG. 4 is a schematic exploded perspective view illustrating a body inwhich a dielectric layer and an internal electrode are stacked,according to an embodiment of the present disclosure.

FIG. 5 is an enlarged view of region P of FIG. 2 .

FIG. 6 is a schematic diagram illustrating a grain having a core-dualshell structure.

FIG. 7 illustrates intensities of Y measured as results of X-rayfluorescence (XRF) Energy Dispersive Endoscopy (EDS) line analysis forgrains having a core-dual shell structure of the Inventive Example ofTest No. 2.

FIG. 8 illustrates intensities of Dy measured as results of XRF EDS lineanalysis for grains having a core-dual shell structure of the InventiveExample of Test No. 2.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to specific embodiments and the accompanying drawings.However, embodiments of the present disclosure may be modified to havevarious other forms, and the scope of the present disclosure is notlimited to the embodiments described below. Further, embodiments of thepresent disclosure may be provided for a more complete description ofthe present disclosure to the ordinary artisan. Therefore, shapes andsizes of the elements in the drawings may be exaggerated for clarity ofdescription, and the elements denoted by the same reference numerals inthe drawings may be the same elements.

A value used to describe a parameter such as a 1-D dimension of anelement including, but not limited to, “length,” “width,” “thickness,”diameter,” “distance,” “gap,” and/or “size,” a 2-D dimension of anelement including, but not limited to, “area” and/or “size,” a 3-Ddimension of an element including, but not limited to, “volume” and/or“size”, and a property of an element including, not limited to,“roughness,” “density,” “weight,” “weight ratio,” and/or “molar ratio”may be obtained by the method(s) and/or the tool(s) described in thepresent disclosure. The present disclosure, however, is not limitedthereto. Other methods and/or tools appreciated by one of ordinary skillin the art, even if not described in the present disclosure, may also beused.

In the drawings, portions not related to the description will be omittedfor clarification of the present disclosure, and a thickness may beenlarged to clearly show layers and regions. Further, throughout thespecification, when an element is referred to as “comprising” or“including” an element, it means that the element may further includeother elements as well, without departing from the description, unlessspecifically stated otherwise.

In the drawings, an X direction may be defined as a second direction, anL direction, or a longitudinal direction; a Y direction may be definedas a third direction, a W direction, or a width direction; and a Zdirection may be defined as a first direction, a stacking direction, a Tdirection, or a thickness direction.

Ceramic Electronic Component

FIG. 1 is a schematic perspective view illustrating a ceramic electroniccomponent according to an embodiment of the present disclosure.

FIG. 2 is a schematic cross-sectional view taken along line I-I′ in FIG.1 .

FIG. 3 is a schematic cross-sectional view taken along line II-II′ ofFIG. 1 .

FIG. 4 is a schematic exploded perspective view illustrating a body inwhich a dielectric layer and an internal electrode are stacked,according to an embodiment of the present disclosure.

FIG. 5 is an enlarged view of region P of FIG. 2 .

FIG. 6 is a schematic diagram illustrating a grain having a core-dualshell structure.

Hereinafter, a ceramic electronic component 100 according to anembodiment of the present disclosure will be described in detail withreference to FIGS. 1 to 6 . Also, a multilayer ceramic capacitor will bedescribed as an example of a ceramic electronic component, but thepresent disclosure is not limited thereto. In addition, a ceramicelectronic component using a ceramic material such as a capacitor, aninductor, a piezoelectric element, a varistor, a thermistor, or the likemay be also applied.

A ceramic electronic component 100 according to the embodiment includesa body 110, including a dielectric layer 111 and an internal electrode121 or 122, and an external electrode 131 or 132 disposed on the body110 and connected to the internal electrode 121 or 122. The dielectriclayer 111 includes a plurality of dielectric grains 10 a, 10 b, and 10c. At least one of the plurality of dielectric grains 10 a, 10 b, and 10c has a core-dual shell structure having a core C and a dual shell. Thedual shell includes a first shell S1, surrounding at least a portion ofthe core C, and a second shell S2 surrounding at least a portion of thefirst shell S1. The dual shell includes different types of rare earthelements R1 and R2, and R2_(S1)/R1_(S1) is 0.01 or less andR2_(S2)/R1_(S1) is 0.5 to 3.0, where R1_(S1) and R1_(S2) denoteconcentrations of R1 included in the first shell and the second shell,respectively, and R2_(S1) and R2_(S2) denote concentrations of R2included in the first shell and the second shell, respectively. Theconcentrations of the rare earth elements R1 and R2 included in thefirst shell and the second shell may be measured using the XRF EDS lineanalysis. The intensity of the rare earth elements R1 and R2 detectedusing the XRF EDS line analysis may be used to calculate R2_(S1)/R1_(S1)and R2_(S2)/R1_(S1). R2_(S1)/R1_(S1) and R2_(S2)/R1_(S1) are a ratio ofmole.

In the body 110, a plurality of dielectric layers 111 may be alternatelystacked with the internal electrode 121 or 122.

Although a specific shape of the body 110 is not necessarily limited, asillustrated, the body 110 may have a hexahedral shape or the like. Dueto shrinkage of ceramic powder particles contained in the body 110during a sintering process, the body 110 may not have a perfectlyhexahedral shape with completely straight lines, but may have asubstantially hexahedral shape overall.

The body 110 may have first and second surfaces 1 and 2 opposing eachother in a thickness direction (the Z direction), third and fourthsurfaces 3 and 4 connected to the first and second surfaces 1 and 2 andopposing each other in a length direction (the X direction), and fifthand sixth surfaces 5 and 6 connected to the first and second surfaces 1and 2, connected to the third and fourth surfaces 3 and 4, and opposingeach other in a width direction (the Y direction).

A plurality of dielectric layers 111 forming the body 110 may be in asintered state, and adjacent dielectric layers 111 may be integratedwith each other such that boundaries therebetween are not readilyapparent without using a scanning electron microscope (SEM).

Referring to FIG. 5 , each dielectric layer 111 may include a pluralityof dielectric grains including 10 a, 10 b, and 10 c, and at least one ofthe plurality of dielectric grains may be a dielectric grain 10 a havinga core-dual shell structure.

Referring to FIG. 6 , the dielectric grain 10 a having the core-dualshell structure may include a first shell S1 surrounding at least aportion of a core C, and a second shell S2 surrounding at least aportion of the first shell S1.

Referring to FIG. 6 , the dielectric grain 10 a having the core-dualshell structure may include a first shell S1, surrounding at least aportion of a core C, and a second shell S2 surrounding at least aportion of the first shell S1.

Development of multilayer ceramic capacitors (MLCC), as an example of acommon ceramic electronic component, has focused on increasingcapacitance and ultra-thinning of layers of MLCCs.

With the increase in capacitance and the ultra-thinning in layers, ithas become increasing difficult to secure withstand voltagecharacteristics of a dielectric layer in the multilayer ceramiccapacitor, and an increase in a defect rate caused by deterioration ofinsulation resistance of a dielectric layer has emerged as an issue.

To address the above issues, a method in which a rare earth element suchas Dy, Y, Ho, or the like, is added to suppress the generation of oxygenvacancies, to reduce mobility of the oxygen vacancies, and to removeelectrons generated by the addition of a transition metal, has beenproposed.

However, when layers in the multilayer ceramic capacitor are thinned tohave higher capacitance or when a high voltage is used therein undermore severe use environments, there have still been issues which cannotbe addressed by the above method.

Therefore, in the present disclosure, at least one of the plurality ofdielectric grains has a core-dual shell structure. In the core-dualshell structure, a ratio of a concentration of a rare earth elementincluded in the first shell and a concentration of a rare earth elementincluded in the second shell may be controlled to secure better hightemperature lifespan characteristics and temperature coefficient ofcapacitance (TCC) characteristics.

Therefore, in the present disclosure, at least one of the plurality ofdielectric grains has a core-dual shell structure. In the core-dualshell structure, a dual shell may include different types of rare earthelements R1 and R2, and R2 may almost not be included in the firstshell. In addition, a ratio of a concentration of R1 included in thefirst shell and a concentration of R2 included in the second shell maybe controlled to secure high-temperature lifespan characteristics andTCC characteristics.

A rare earth element may basically replace an A site having a perovskitestructure, represented by ABO₃, such that an oxygen vacancyconcentration is reduced to form a cell region. The shell region may actas a barrier to prevent electrons from flowing at grain boundaries ofdielectric grains, to prevent the leakage current.

As illustrated in FIGS. 5 and 6 , the first shell S1 may be disposed tocover an entire surface of the core C, and the second shell S2 may bedisposed to cover an entire surface of the first shell S2. However, thefirst shell S1 may not cover a portion of a surface of the core C, andthe second shell S2 may be directly deposited on the portion of thesurface of the core C where the first shell S1 is not covered. Also, thesecond shell S2 may not cover a portion of a surface of the first shellS1.

In this case, the first shell S1 may be disposed to cover at least 90area % of the surface of the core C, and the second shell S2 may bedisposed to cover at least 90 area % of the surface of the first shellS1. This is because when the first shell S1 is disposed to cover lessthan 90 area % of the surface of the core and/or the second shell S2 isdisposed to cover less than 90 area % of the surface of the first shellS1, the effect of improving reliability according to the presentdisclosure may not be sufficient.

The dual shell includes different types of rare earth elements R1 andR2. A concentration of R1 included in the first shell S1 may be definedas R1_(S1), a concentration of R1 included in the second shell S2 may bedefined as R1_(S2), a concentration of R2 included in the first shell S1may be defined as R2_(S1), and a concentration of R2 included in thesecond shell S2 may be defined as R2_(S2).

A ratio of the concentration of R2 included in the first shell S1 to theconcentration of R1 included in the first shell S1 (R2_(S1)/R1_(S1)) is0.01 or less (including 0). For example, R2 is substantially notincluded in the first shell S1. When R2_(S1)/R1_(S1) is greater than0.01, the effect of improving reliability according to the presentdisclosure may not be sufficient.

In addition, a ratio of the concentration of R2 included in the firstshell S2 to the concentration of R1 included in the first shell S1(R2_(S2)/R1_(S1)) satisfies 0.5 to 3.0.

When R2_(S2)/R1_(S1) is less than 0.5, the effect of improvingreliability according to the present disclosure may not be sufficient.When R2_(S1)/R1_(S1) is greater than 3.0, a secondary phase may beformed by a rare earth element to deteriorate reliability.

When R2_(S2)/R1_(S1) satisfies 0.5 to 3.0, a ratio of the concentrationof R1 included in the second shell S2 to the concentration of R1included in the first shell S1 (R1_(S2)/R1_(S1)) may satisfy 0.1 to 1.3.

When R1_(S2)/R1_(S1) is less than 0.1, abnormal grain growth may beinduced, and thus, coarse grains may be formed to deterioratereliability. Meanwhile, when R1_(S2)/R1_(S1) is greater than 1.3, asecondary phase may be formed by a rare earth element to deterioratereliability.

In the core C, no rare earth element may be included or a significantlysmall amount of rare earth element may be included.

In addition, since the concentration of R1 or R2 dramatically changes ata boundary between the core C and the first shell S1 and dramaticallychanges at a boundary between the first shell S1 and the second shellS2, the core C, the first shell S1, and the second shell S2 may beeasily distinguished, and may be confirmed through Transmission ElectronMicroscopy Energy Dispersive Spectroscopy (TEM-EDS) analysis.

Referring to FIG. 6 , a distance LS2 corresponding to the thickness ofthe second shell S2 along a straight line connecting α and β may begreater than 4% to less than 25% of a distance between α and β, where αdenotes a center of the core-dual shell structure in the cross-sectionof the core-dual shell structure, and β denotes a point on an outersurface of the second shell, farthest from α. In this case, α may referto a center of gravity of the dielectric grain in a cross-section. Thedistances LS2 is measured using TEM-EDS. The distance LS2 can bemeasured by a method other than the TEM-EDS method, which is appreciatedby the one skilled in the art.

When the distance LS2 corresponding to the thickness of the second shellS2 along the straight line connecting α and β is 4% or less, the effectof improving reliability may not be sufficient, and the effect ofimproving high-temperature lifespan characteristics and the dielectricconstant may be deteriorated.

Meanwhile, when the distance LS2 corresponding to the thickness of thesecond shell along the straight line connecting α and β is 25% or more,the high temperature lifespan characteristics may be deteriorated or thetemperature coefficient of capacitance (TCC) characteristics dependingon a change in temperature may be deteriorated.

In this case, a distance LS1 corresponding to the thickness of the firstshell S1 along the straight line connecting α and β may be 5% or more to30% or less of the distance between α and β.

When the distance LS1 corresponding to a thickness of the first shell S1along the straight lines connecting α and β is less than 5%, it may bedifficult to implement a dual shell structure. When the distance LS1corresponding to a thickness of the first shell S1 along the straightlines connecting α and β exceeds 30%, it may be difficult to securereliability. The distances LS1 is measured using TEM-EDS. The distanceLS1 can be measured by a method other than the TEM-EDS method, which isappreciated by the one skilled in the art.

In addition, when a length of the first shell S1 is quite different froma length of the second shell S2, it may be difficult to simultaneouslyimprove the high-temperature lifespan characteristics and the TCCcharacteristics. Therefore, the length LS1 corresponding to a thicknessof the first shell, among the straight lines connecting α and β, may be0.5 to 1.5 times the length LS2 corresponding to a thickness of thesecond shell S2, among the straight lines connecting α and β.

Referring to FIG. 5 , the dielectric layer 111 may include a dielectricgrain 10 b having a core-shell structure, in addition to the dielectricgrain 10 a having the core-dual shell structure. Therefore, at least oneor more of a plurality of dielectric grains may be the dielectric grain10 b having the core-shell structure. The dielectric grain 10 b havingthe core-shell structure may include a core 10 b 1 and a shell 10 b 2surrounding at least a portion of the core 10 b 1.

In addition, the dielectric layer 111 may include a dielectric grain 10c having no shell.

When the dielectric layer 111 includes the dielectric grain 10 c havingno shell, the number of the dielectric grains 10 a having the core-dualshell structure may be 50% or more with respect to the total number ofthe dielectric grains including 10 a, 10 b, and 10 c. A ratio of thenumber of dielectric grains having the core-dual shell structure may bemeasured in an image of a cross-section of the dielectric layer scannedby a transmission electron microscope (TEM).

When the number of the dielectric grains having the core-dual shellstructure, among the plurality of dielectric grains, is less than 50%,the effect of improving high temperature lifespan characteristics andthe TCC characteristic may be not sufficient.

The dielectric layer 111 may include a material having a perovskitestructure represented by ABO₃ as a main component.

For example, the dielectric layer 111 may include one or more of BaTiO₃,(Ba,Ca)(Ti,Ca)O₃, (Ba,Ca)(Ti,Zr)O₃, Ba(Ti,Zr)O₃, or (Ba,Ca)(Ti,Sn)O₃ asa main component.

More specifically, for example, the dielectric layer 111 may include oneor more selected from the group consisting of BaTiO₃,(Ba_(1-x)Ca_(x))(Ti_(1-y)Ca_(y))O₃ (where 0≤x≤0.3, 0≤y≤0.1),(Ba_(1-x)Ca_(x))(Ti_(1-y)Zr_(y))O₃ (where 0≤x≤0.3, 0≤y≤0.5),Ba(Ti_(1-y)Zr_(y))O₃ (where 0<y≤0.5), or (Ba_(1-x)Ca_(x))(Ti_(1-y)Sn_(y))O₃ (where 0≤x≤0.3, 0≤y≤0.1), as main components.

A sum of contents of R1 and R2 included in the dielectric layer 111 maybe in a range of 0.1 to 15 moles, relative to 100 moles of the maincomponent.

When the sum of the contents of R1 and R2 included in the dielectriclayer 111 is less than 0.1 mole, relative to 100 moles of the maincomponent, it may be difficult to implement the core-dual shellstructure. When the sum of the contents of R1 and R2 included in thedielectric layer 111 is greater than 15 moles, relative to 100 moles ofthe main component, the sintering temperature may be significantlyincreased. Therefore, it may be difficult to obtain a densemicrostructure.

The content of each of R1 and R2 included in the dielectric layer 111 isnot necessarily limited. However, in one embodiment of the presentdisclosure, the content of R1 included in the dielectric layer 111 maybe 0.1 to 4.0 moles, relative to 100 moles of the main component, andthe content of R2 included in the dielectric layer 111 may be 0.01 to 12moles, relative to 100 moles of the main component. In further detail,the content of R1 included in the dielectric layer III may be 0.1 to 2.5moles, relative to 100 moles of the main component, and the content ofR2 included in the dielectric layer 111 may be 0.01 to 7.5 moles,relative to 100 moles of the main component.

In this case, R1 may be at least one selected from the group consistingof lanthanum (La), yttrium (Y), actinium (Ac), cerium (Ce), praseodymium(Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium(Er), thulium (Tm), ytterbium (Yb), or ruthenium (Ru), and R2 may be atleast one selected from the group, which is not the element included inR1.

In addition, the present disclosure is not limited thereto. However, theelement selected from the group, which is included in R2, has a largerionic radius than the element selected from the group included in R1.This is because when the element included in R2 has a larger ionicradius than the element included in R1, there may be an effect of moreeasily implementing a core-double shell structure according to thepresent disclosure.

In addition, minor components included in the dielectric layer 111 donot need to be limited except that rare earth elements should beincluded in the dielectric layer 111, and appropriate elements andcontents may be determined to obtain desired characteristics. Forexample, the dielectric layer may further include at least one of Mn,Cr, Ba, Si, Al, Mg, or Zr, as a minor component.

A size of the dielectric grains is not necessarily limited. For example,an average grain size of the dielectric grains in the dielectric layer111 may be 50 nm or more to 500 nm or less. The size of the averagegrain size can be measured by a method other than the Feret diametermethod, which is appreciated by the one skilled in the art.

When an average grain size is less than 50 nm, an expected effectdepending on deficiency in dissolution of an added element, caused by adecrease in dielectric constant and a decrease in grain growth rate, maybe insufficient. When the average grain size is greater than 500 nm, achange in capacitance depending on a temperature and a DC voltage may beincreased and reliability may be deteriorated due to a decrease in thenumber of dielectric grains per unit volume of dielectric layer.

The body 110 may include a capacitance formation portion A disposed inthe body 110 and including a first internal electrode 121 and a secondinternal electrode 122 disposed to oppose each other with respectivedielectric layers 111 interposed therebetween, to form capacitance andcover portions 112 and 113, respectively formed above and below thecapacitance formation portion A.

In addition, the capacitance formation portion A may be a portioncontributing to capacitance formation of a capacitor, and may be formedby repeatedly and alternately laminating the plurality of first andsecond internal electrodes 121 and 122 with respective dielectric layers111 interposed therebetween.

An upper cover portion 112 and a lower cover portion 113 may be formedby laminating a single dielectric layer or two or more dielectric layerson upper and lower surfaces of the capacitance formation portion in avertical direction, respectively, and may basically serve to physical orchemical damage to prevent the internal electrodes 121 and 122 frombeing damaged by external physical or chemical stress.

The upper cover portion 112 and the lower cover portion 113 may notinclude internal electrodes, and may include the same material as thedielectric layer 111.

For example, the upper cover portion 112 and the lower cover portion 113may include a ceramic material, for example, may include a bariumtitanate (BaTiO₃)-based ceramic material.

In addition, margin portions 114 and 115 may be disposed on sidesurfaces of the capacitance formation portion A.

The margin portions 114 and 115 may be disposed on the sixth surface 6of the body 110, and a margin portion 115 may be disposed on the fifthsurface 5 of the body 110. For example, the margin portions 114 and 115may be disposed on both side surfaces of the body 110 opposing eachother in the width direction.

As illustrated in FIG. 3 , the margin portions 114 and 115 may refer toa region between ends of the first and second internal electrodes 121and 122, in the cross-section of the body 110 cut in width-thickness(W-T) directions, and a boundary surface of the body 110.

The margin portions 114 and 115 may basically serve to prevent damage tothe internal electrode due to external physical or chemical stress.

The margin portions 114 and 115 may be formed by applying a conductivepaste to a ceramic green sheet at a region in which a margin portion isto be formed.

To suppress a step formed by the internal electrodes 121 and 122, aftera lamination operation, the internal electrodes may be cut to be exposedfrom the fifth and sixth surfaces 5 and 6 of the body 110. Then, asingle dielectric layer or two or more dielectric layers may belaminated on both exposed surfaces of the capacitance formation portionA in the width direction to form the margin portions 114 and 115.

The internal electrodes 121 and 122 may be alternately laminated withthe dielectric layer 111.

The internal electrodes 121 and 122 may include first internalelectrode(s) 121 and second internal electrode(s) 122. The first andsecond internal electrodes 121 and 122 may be alternately arranged tooppose each other with respective dielectric layers 111, constitutingthe body 110, interposed therebetween, and may respectively be exposedto the third and fourth surfaces 3 and 4 of the body 110.

Referring to FIG. 2 , the first internal electrode(s) 121 may be spacedapart from the fourth surface 4 and may be exposed from the thirdsurface 3, and the second internal electrode(s) 122 may be spaced apartfrom the third surface 3 and may be exposed from the fourth surface 4.

In this case, the first and second internal electrodes 121 and 122 maybe electrically separated from each other by respective dielectriclayers 111 interposed therebetween.

Referring to FIG. 3 , the body 110 may be formed by alternatelylaminating a ceramic green sheet, on which the first internal electrode121 is printed, and a ceramic green sheet, on which the second internalelectrode 122 is printed, and then sintering the laminated ceramic greensheet laminate.

A material for forming the internal electrodes 121 and 122 is notnecessarily limited, and a material having improved electricalconductivity may be used. For example, the internal electrodes 121 and122 may be formed by printing a conductive paste for the internalelectrodes including at least one of nickel (Ni), copper (Cu), palladium(Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), tungsten (W),titanium (Ti), and alloys thereof, on the ceramic green sheet.

A screen-printing method, a gravure printing method, or the like, may beused as a printing method of the conductive paste for the internalelectrodes, but the present disclosure is not limited thereto.

To achieve miniaturization and high capacitance of the multilayerceramic capacitor, thicknesses of the dielectric layer(s) and theinternal electrode(s) should be thinned to increase the number oflaminated layers. Therefore, as the dielectric layer(s) and the internalelectrode(s) are thinned, reliability may be deteriorated, andcharacteristics such as an insulation resistance, breakdown voltage, orthe like, may be deteriorated.

Therefore, as the dielectric layer(s) and the internal electrode(s) arethinned, the effect of improving reliability according to the presentdisclosure may be improved.

In particular, when a thickness (te) of the internal electrode 121 and122 or a thickness (td) of the dielectric layer(s) 111 is 0.41 μm orless, the effect of improving high-temperature lifespan characteristicsand the TCC characteristics according to the present disclosure may besignificantly improved.

The thickness (te) of the internal electrodes 121 and 122 may refer toan average thickness of the first and second internal electrodes 121 and122.

The thickness (te) of the internal electrodes 121 and 122 may bemeasured by scanning an image of a cross-section in the third and firstdirections (an L-T cross-section) of the body 110 by a scanning electronmicroscope (SEM).

For example, on the basis of a reference internal electrode layer at apoint at which a center line in the longitudinal direction of the bodyand a center line in the thickness direction of the body meet, athickness (te) of the internal electrodes 121 and 122 may be determinedby defining two points to the left and two points to the right from areference center point in the reference internal electrode layer atequal intervals, measuring a thickness of each of the defined points,and obtaining an average value therefrom, for five internal electrodelayers including the reference internal electrode layer, and two upperinternal electrode layers and two lower internal electrode layers,respectively arranged on and below the reference internal electrodelayer, among the internal electrode layers extracted from an image of across-section in the third and first directions (an L-T cross-section)of the body 110, cut in a central portion of the body 110 in the widthdirection, scanned by a scanning electron microscope (SEM).

For example, since a thickness at the reference center point in thereference internal electrode layer at a point at which a center line inthe longitudinal direction of the body and a center line in thethickness direction of the body meet, and a thickness (each 500 nm) ateach of the two points to the left and right from the reference centerpoint at equal intervals, for the above five internal electrode layers,may be measured, the thickness (te) of the internal electrodes 121 and122 may be determined as an average value of the thicknesses of a totalof 25 points.

The thickness (td) of the dielectric layer 111 may refer to an averagethickness of the dielectric layer(s) 111 disposed between the first andsecond internal electrodes 121 and 122.

Similarly to the thickness (te) of the internal electrode, the thickness(td) of the dielectric layer 111 may be measured by scanning an image ofa cross-section in the third and first directions (an L-T cross-section)of the body 110 by a scanning electron microscope (SEM).

For example, on the basis of a reference dielectric layer at a point atwhich a center line in the longitudinal direction of the body and acenter line in the thickness direction of the body meet, a thickness(td) of the dielectric layer 111 may be determined by defining twopoints to the left and two points to the right from a reference centerpoint in the reference dielectric layer at equal intervals, measuring athickness of each of the defined points, and obtaining an average valuetherefrom, for five dielectric layers including the reference dielectriclayer, and two upper dielectric layers and two lower dielectric layers,respectively arranged on and below the reference dielectric layer, amongthe dielectric layers extracted from an image of a cross-section in thethird and first directions (an L-T cross-section) of the body 110, cutin a central portion of the body 110 in the width direction, scanned bya scanning electron microscope (SEM).

For example, since a thickness at the reference center point in thereference dielectric layer at a point at which a center line in thelongitudinal direction of the body and a center line in the thicknessdirection of the body meet, and a thickness (each 500 nm) at each of thetwo points to the left and right from the reference center point atequal intervals, for the above five dielectric layers, may be measured,the thickness (td) of the dielectric layer 111 may be determined as anaverage value of the thicknesses of a total of 25 points.

The external electrodes 131 and 132 may be arranged on the body 110, andmay be connected to the internal electrodes 121 and 122, respectively.

As illustrated in FIG. 2 , first and second external electrodes 131 and132 may be disposed on the third and fourth surfaces 3 and 4 of the body110, respectively, and may be connected to the first and second internalelectrodes 121 and 122, respectively.

In this embodiment, a structure in which the ceramic electroniccomponent 100 has two external electrodes 131 and 132 has beendescribed, but the number, shape, and the like of the externalelectrodes 131 and 132 may be changed, depending on shapes of theinternal electrodes 121 and 122, or other purposes.

The external electrodes 131 and 132 may be formed using any material aslong as they have electrical conductivity such as metal, a specificmaterial may be determined in consideration of electricalcharacteristics, structural stability, and the like, and may have amultilayer structure.

For example, the external electrodes 131 and 132 may include electrodelayers 131 a and 132 a, and plating layers 131 b and 132 b formed on theelectrode layers 131 a and 132 a, respectively.

As a more specific example of the electrode layers 131 a and 132 a, theelectrode layers 131 a and 132 a may be sintered electrodes including aconductive metal and a glass, or resin-based electrodes including aconductive metal and a resin.

In addition, the electrode layers 131 a and 132 a may have a form inwhich the sintered electrode and the resin-based electrode aresequentially formed on the body 110. In addition, the electrode layers131 a and 132 a may be formed by transferring a sheet including theconductive metal on the body 110, or may be formed by transferring thesheet including the conductive metal on the sintered electrode.

The conductive metal used for the electrode layers 131 a and 132 a isnot particularly limited as long as it is a material that may beelectrically connected to the internal electrode(s) to form capacitance.For example, the conductive metal may be one or more of nickel (Ni),copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin(Sn), tungsten (W), titanium (Ti), and alloys thereof.

The plating layers 131 b and 132 b may be plating layers including atleast one of nickel (Ni), tin (Sn), palladium (Pd), and alloys thereof,and may include a plurality of layers.

As a more specific example of the plating layers 131 b and 132 b, theplating layers 131 b and 132 b may be nickel (Ni) plating layers or tin(Sn) plating layers, may have a form in which the nickel (Ni) platinglayers and the tin (Sn) plating layers are sequentially formed on theelectrode layers 131 a and 132 a, and may have a form in which a tin(Sn) plating layer, a nickel (Ni) plating layer, and another tin (Sn)plating layer are formed sequentially. In addition, the plating layers131 b and 132 b may include a plurality of nickel (Ni) plating layersand/or a plurality of tin (Sn) plating layers.

Method of Manufacturing Ceramic Electronic Component

Hereinafter, a method of manufacturing a ceramic electronic componentaccording to another aspect of the present disclosure will be describedin detail. However, descriptions overlapping those described in theceramic electronic component will be omitted to avoid overlappingdescriptions.

According to another aspect of the present disclosure, a method ofmanufacturing a ceramic electronic component includes preparing a basematerial powder having a core-shell structure having a core and a shell,the shell including a rare earth element R1, adding a minor componentincluding another type of rare earth element R2, different from the rareearth element R1, to the base material powder to prepare a ceramic greensheet, printing a conductive paste for an internal electrode on theceramic green sheet, and then laminating the printed ceramic green sheetto prepare a laminate, sintering the laminate to prepare a bodyincluding a dielectric layer and an internal electrode, and forming anexternal electrode on the body. A content of R2 in the base materialpowder is 0.1 to 3.0 times a content of R1.

A base material powder, having a core-shell structure having a core anda shell, the shell including a rare earth element, may be prepared.

When the base material powder does not have the core-shell structure, itmay be difficult to implement dielectric grains having a core-dual shellstructure according to the present disclosure.

The method of manufacturing the base material powder having thecore-shell structure is not necessarily limited. For example, whenBaTiO₃ is prepared by a hydrothermal synthesis process, a rare earthelement may be added, during a process of growing the powder to adesired size, to synthesize the base material powder. Alternatively,after mixing the BaTiO₃ with the rare earth element, the base materialpowder having the core-shell structure may be prepared through heattreatment.

Next, a minor component including a rare earth element R2, differentfrom the rare earth element R1, may be added to the base material powderto prepare a ceramic green sheet. In this case, after adding the minorcomponent to the base material powder, ethanol and toluene as a solventmay be mixed with a dispersant, and a binder may be further mixedtherewith to produce a ceramic sheet.

To implement dielectric grains having a core-dual shell structureaccording to the present disclosure, a content of the rare earth elementR2 included in the base material powder as a minor component may becontrolled to be 0.1 to 3.0 times a content of the rare earth element R1included in the base material powder.

When the content of R2 is less than 0.1 times the content of R1 includedin the base material powder, it may be difficult to implement dielectricgrains having a core-dual shell structure according to the presentdisclosure. When the content of R2 is greater than 3.0 times the contentof R1 included in the base material powder, a secondary phase may beformed by a rare earth element to deteriorate reliability.

Elements included in the minor component, except for the rare earthelement, are not necessarily limited and may be appropriately controlledto obtain desired characteristics.

Next, after printing an electrically conductive paste for internalelectrodes on the ceramic sheet, a plurality of printed ceramic sheetsmay be laminated to prepare a laminate.

Next, the laminate may be sintered to prepare a body includingdielectric layer(s) and internal electrode(s).

The dielectric layer 111 includes a plurality of dielectric grains 10 a,10 b, and 10 c. At least one of the plurality of dielectric grains 10 a,10 b, and 10 c has a core-dual shell structure having a core C and adual shell. The dual shell includes a first shell S1, surrounding atleast a portion of the core C, and a second shell S2 surrounding atleast a portion of the first shell S1. The dual shell includes at leasttwo different types of rare earth elements R1 and R2, andR2_(S1)/R1_(S1) is 0.01 or less and R2_(S2)/R1_(S1) is 0.5 to 3.0, whereR1_(S1) and R1_(S2) denote concentrations of R1 included in the firstshell and the second shell, respectively, and R2_(S1) and R2_(S2) denoteconcentrations of R2 included in the first shell and the second shell,respectively.

To satisfy the above relationship in which R2_(S1)/R1_(S1) is 0.01 orless and R2_(S2)/R1_(S1) is 0.5 to 3.0, a sintering temperature as wellas contents of rare earth elements, added to the base material powder asthe minor components, needs to be appropriately adjusted.

A specific numerical range of the sintering temperature may varydepending on types and amounts of added elements, but is not necessarilylimited. For example, the range of the sintering temperature may be morethan 1230° C. to less than 1280° C.

Next, an external electrode may be formed on the body to obtain aceramic electronic component.

Example

Base material powders, listed in Table 1 below, were prepared. In thiscase, “1.5Y doped BT” refers to a base material powder, having acore-shell structure, in which 1.5 mole of Y is included in a shellportion, relative to 100 moles of BaTiO₃. In addition, “0.5Ho doped BT”refers to a base material powder, having a core-shell structure, inwhich 0.5 mole of Ho is included in a shell portion, relative to 100moles of BaTiO₃. In addition, “Non doped BT” refers to a BaTiO₃ powderhaving no core-shell structure.

Then, minor components, listed in Table 1 below, were added to the basematerial power and mixed with a dispersant using ethanol and toluene asa solvent. Then, a binder was further mixed therewith to prepare aceramic sheet. A nickel (Ni) electrode was printed on the preparedceramic sheet, and a plurality of printed ceramic sheets were laminated,pressed, and cut to prepare a plurality of chips. The plurality of chipswere plasticized to remove the binder, and a sintering operation wasthen performed under a reducing atmosphere at a sintering temperatures,listed in Table 1, to prepare sample chips.

Dielectric constants, 125° C. TCC values, and high-temperature lifespancharacteristics of the prepared sample chips were measured and arelisted in Table 2 below.

In each of the listed samples, a structure of a dielectric grain wasanalyzed through TEM-EDS analysis and is listed in Table 2.

The 125° C. TCC values were measured using an LCR meter at a temperaturerange of −55° C. to 125° C. at 1 kHz and 1 V.

Tests for high-temperature lifespan characteristics (high-temperature IRboosting tests) were performed on 40 samples for each test number bymaintaining conditions including 150° C. and 1 Vr=10 V/μm for 30minutes, increasing voltages in times, and calculating an averaged offailure voltage values, and the calculated average values are listed. Inthis case, “1 Vr” refers to 1 reference voltage, and “10 V/μm” refers toa voltage of 10 volts per 1 μm, a thickness of a dielectric substance.

In addition, cross-sections of the sample chips in length and thicknessdirections (L-T cross-sections), cut in a central portion of each of thesample chips in the width direction, were analyzed by a transmissionelectron microscope (TEM) and an energy dispersive X-ray spectroscopy(EDS) apparatus to list Concentrations 1*, Concentrations 2* Lengths*,and Fractions* in Table 2. The TEM was 200 kV ARM, and was confirmedwith spot 4, 100,000 times. STEM-EDS was measured with 100 points atintervals of 10 nm.

Concentrations 1* and Concentrations 2* were determined by performingline analysis of an energy dispersive X-ray spectroscopy (EDS), mountedon a transmission electron microscope (TEM), on grains each having acore-dual shell structure to obtain an intensity value for each of Y andDy. Concentrations 1* were obtained by dividing a value R1_(S2),obtained by subtracting the intensity of Y in a core region from theintensity of Y in a second shell, by a value R1_(S1) obtained bysubtracting the Y intensity of the core region from the intensity of Yin a first shell. Concentrations 2* were obtained by dividing a valueR2_(S2), obtained by subtracting the intensity of Dy in the core regionfrom the intensity of Dy in the second shell, by a value R1_(S1)obtained by subtracting the intensity of Y in the core region from theintensity of Y in the first shell.

Lengths* were obtained by performing TEM EDS line analysis on thegrains, each having a core-dual shell structure as illustrated in FIGS.7 and 8 , and results of [the number of points measured in the LS2]/[thetotal number of points measured from α to β] are listed.

Fractions* were obtained by measuring ratios of the number of grainseach having a core-dual shell structure, relative to the total number ofdielectric grains in the 10 μm×10 μm regions, central portions of thecross-sections in the length and thickness directions (L-Tcross-sections).

TABLE 1 Test Base Material Minor Components Sintering Nos. Power (Molesrelative to BT 100 moles of Base Material Powders) Temp. (° C.)  1* 1.5Ydoped BT Dy 1.0, Mn 0.2, Cr 0.1, Ba 2.5, Si 2.5, Al 0.5, 1230 Mg 0.8, Zr0.45 2 Dy 1.0, Mn 0.2, Cr 0.1, Ba 2.5, Si 2.5, Al 0.5, 1250 Mg 0.8, Zr0.45 3 Dy 2.0, Mn 0.2, Cr 0.1, Ba 2.5, Si 2.5, Al 0.5, 1250 Mg 0.8, Zr0.45 4 Dy 0.3, Mn 0.2, Cr 0.1, Ba 2.5, Si 2.5, Al 0.5, 1250 Mg 0.8, Zr0.45  5* Dy 0.1, Mn 0.2, Cr 0.1, Ba 2.5, Si 2.5, Al 0.5, 1250 Mg 0.8, Zr0.45  6* Dy 0.0, Mn 0.2, Cr 0.1, Ba 2.5, Si 2.5, Al 0.5, 1250 Mg 0.8, Zr0.45  7* 0.7Ho doped BT Dy 1.0, Mn 0.15, Ba 2.1, Si 2.2, Al 0.8 Mg 1.0,Zr 0.35 1220 8 Dy 1.0, Mn 0.15, Ba 2.1, Si 2.2, Al 0.8 Mg 1.0, Zr 0.351240 9 Dy 1.0, Mn 0.15, Ba 2.1, Si 2.2, Al 0.8 Mg 1.0, Zr 0.35 1260 10*Dy 1.0, Mn 0.15, Ba 2.1, Si 2.2, Al 0.8 Mg 1.0, Zr 0.35 1280 11* Nondoped BT Y1.5, Dy 1.0, Mn 0.2, Cr 0.1, Ba 2.5, Si 2.5, Al 0.5, 1250 Mg0.8, Zr 0.45 12* Ho0.7, Dy 1.0, Mn 0.15, Ba 2.1, Si 2.2, Al 0.8, 1240 Mg1.0, Zr 0.35

TABLE 2 Test 125° C. High Temp. Lifespan C1* C2* Nos. DC TCCCharacteristics(V/μm) (R1_(S2)/R1_(S1)) (R2_(S2)/R1_(S1)) L F* Note 1*2200  −7% 21 0.8 4.00  4/100 23% CE 2  2400  −8% 78 0.5 1.20  5/100 55%IE 3  2000  −3% 75 1.3 3.00 13/100 82% IE 4  2600 −10% 73 0.1 0.5015/100 75% CE 5* 3200 −19% 31 0.05 0.20 30/100 57% CE 6* 3700 −25% 260.05 — 30/100 52% CE 7* 2500  −9% 29 1.0 1.80  4/100 48% CE 8  2700 −12%62 0.8 1.20 18/100 78% IE 9  2800 −14% 73 0.5 1.00 20/100 75% IE 10* 3400 −23% 13 0.1 0.80 15/100 64% CE 11*  2400  −9% 53 — — — — CE 12* 2900 −15% 50 — — — — CE (DC: Dielectric Constant, C1: Concentration 1,C2: Concentration 2, L: Length, F: Fraction, CE: Comparative Example,and IE: Inventive Example)

As can seen from Tables 1 and 2, Test Nos. 2 to 4, 8, and 9, in whichConcentration 2* satisfied 0.5 to 3.0, had an improved high-temperaturelifespan reliability. In addition, Test Nos. 2 to 4, 8, and 9 had animproved dielectric constant and improved 125° C. TCC characteristics.

Meanwhile, Test Nos. 11 and 12, in which no grain having a core-dualshell structure is included, had poor high-temperature lifespanreliability.

In addition, Test Nos. 1, 5 and 6 had a core-dual shell structure, but avalue of Concentration 2* (R2_(S2)/R1_(S1)) did not satisfy 0.5 to 3.0,and thus, high-temperature lifespan reliability was poor.

In the case of Test No. 7, a value of Concentration 2* (R2_(S2)/R1_(S1))satisfied 0.5 to 3.0, but a second shell had a significantly shortlength or a fraction of a grain having a core-dual shell structure waslow, and thus, high-temperature lifespan reliability was poor.

In the case of Test No. 10, a value of Concentration 2*(R2_(S2)/R1_(S1)) satisfied 0.5 to 3.0, but a value of Concentration 1*(R1_(S2)/R1_(S1)) was low, and thus, high-temperature lifespanreliability was poor.

FIG. 7 illustrates intensities of Y measured as results of XRF EDS lineanalysis for grains having a core-dual shell structure of the InventiveExample of Test No. 2.

In FIG. 7 , intensity of Y in a core portion is approximately 18 onaverage, which indicates that Y is not present in the core portion. Inaddition, intensity of Y and a length LC corresponding to a radius ofthe core portion may vary depending on a TEM apparatus, measurementconditions, and environments, but a portion having a lowest value in themeasured intensity may be regarded as a core region and may be regardedas a portion in which Y is not present.

The intensity of Y in the first shell S1 is approximately 48 on average,and the intensity of Y in the second shell S2 is approximately 33 onaverage. Therefore, R1_(S2)/R1_(S1) may be obtained by dividing a value,obtained by subtracting 18 from the intensity of Y in the second shell,by a value obtained by subtracting 18 from the intensity of Y in thefirst shell. For example, R1_(S2)/R1_(S1)=(33−18)/(48−18)=0.5.

FIG. 8 illustrates intensities of Dy measured as results of XRF EDS lineanalysis for grains having a core-dual shell structure of the InventiveExample of Test No. 2.

In FIG. 8 , intensity of Dy in a core portion and a first shell isapproximately 18 on average, which indicates that Dy is not present inthe core portion and the first shell. In addition, intensity of Dy to alength LC corresponding to a radius of the core portion may varydepending on a TEM apparatus, measurement conditions, and environments,but a portion having a lowest value in the measured intensity may beregarded as a core region and may be regarded as a portion in which Dyis not present.

The intensity of Dy in a second shell S2 is approximately 54 on average.Therefore, R2_(S2)/R1_(S1) may be obtained by dividing a value, obtainedby subtracting 18 from the intensity of Dy in the second shell, by avalue obtained by subtracting 18 from the intensity of Y in the firstshell. For example, R2_(S2)/R1_(S1)=(54-18)/(48-18)=1.20.

As described above, among a plurality of dielectric grains, at least onegrain may have a core-dual shell structure. Thus, reliability of aceramic electronic component may be improved.

In the core-dual shell structure, a concentration of a rare earthelement included in a first shell and a concentration of a rare earthelement included in a second shell may be controlled to improvehigh-temperature lifespan characteristics and TCC characteristics.

While embodiments have been illustrated and described above, it will beapparent to those skilled in the art that modifications and variationscould be made without departing from the scope of the present disclosureas defined by the appended claims.

What is claimed is:
 1. A method of manufacturing a ceramic electroniccomponent, the method comprising: preparing a base material powderhaving a core-shell structure having a core and a shell, wherein theshell includes a rare earth element R1; adding a minor componentincluding a rare earth element R2, which is different from the rareearth element R1, to the base material powder to prepare a ceramic greensheet; printing a conductive paste for an internal electrode on theceramic green sheet, and then laminating the printed ceramic green sheetto prepare a laminate; sintering the laminate to prepare a bodyincluding a dielectric layer and an internal electrode; and forming anexternal electrode on the body, wherein a content of R2 is 0.1 to 3.0times a content of R1, the dielectric layer includes a plurality ofdielectric grains, at least one of the plurality of dielectric grainshas a core-dual shell structure having a core and a dual shell, the dualshell includes a first shell surrounding at least a portion of the core,and a second shell surrounding at least a portion of the first shell,the dual shell includes at least two different types of rare earthelements R1 and R2, and R2_(S1)/R1_(S1) is 0.01 or less, R2_(S2)/R1_(S1)is 0.5 to 3.0, and R1_(S2)/R1_(S1) is 0.1 to 1.3, where R1_(S1) andR1_(S2) denote concentrations of R1 included in the first shell and thesecond shell, respectively, and R2_(S1) and R2_(S2) denoteconcentrations of R2 included in the first shell and the second shell,respectively, and a distance corresponding to a thickness of the secondshell along a straight line connecting α and β is greater than 4% toless than 25% of a distance between α and β, where a denotes a center ofthe core-dual shell structure in the cross-section of the core-dualshell structure, and β denotes a point on a surface of the second shell,farthest from α.
 2. The method of claim 1, wherein the sintering thelaminate is performed by adjusting a sintering temperature such thatR2_(S1)/R1_(S1) is 0.01 or less, and R2_(S2)/R1_(S1) is 0.5 to 3.0. 3.The method of claim 2, wherein the sintering temperature is more than1230° C. to less than 1280° C.
 4. The method of claim 1, wherein adistance corresponding to a thickness of the first shell along thestraight line connecting α and β is 5% or more to 30% or less.
 5. Themethod of claim 1, wherein a distance corresponding to a thickness ofthe first shell along the straight line connecting α and β is 0.5 ormore to 1.5 or less times the distance corresponding to a thickness ofthe second shell along the straight line connecting α and β.
 6. Themethod of claim 1, wherein the first shell of the core-dual shellstructure is disposed to cover 90% or more of a surface area of thecore, and the second shell of the core-dual shell structure is disposedto cover 90% or more of a surface area of the first shell.
 7. The methodof claim 1, wherein at least one of the plurality of dielectric grainshas a core-shell structure having a core and a shell.
 8. The method ofclaim 1, wherein a number of dielectric grains having the core-dualshell structure is 50% or more of a number of the plurality ofdielectric grains.
 9. The method of claim 1, wherein R1 comprises atleast one selected from the group consisting of lanthanum (La), yttrium(Y), actinium (Ac), cerium (Ce), praseodymium (Pr), neodymium (Nd),promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium(Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm),ytterbium (Yb), and ruthenium (Ru), and R2 comprises at least oneselected from the group, other than the element included in R1.
 10. Themethod of claim 1, wherein R2 has a larger ionic radius than R1.
 11. Themethod of claim 1, wherein the dielectric layer includes one or more ofBaTiO₃, (Ba,Ca) (Ti,Ca)O₃, (Ba,Ca) (Ti,Zr)O₃, Ba (Ti,Zr)O₃, or (Ba,Ca)(Ti,Sn)O₃ as a main component.
 12. The method of claim 11, wherein a sumof contents of R1 and R2 included in the dielectric layer is 0.1 to 15mole relative to 100 moles of the main component.
 13. The method ofclaim 11, wherein the dielectric layer further includes at least one ofMn, Cr, Ba, Si, Al, Mg, or Zr, as a minor component.
 14. The method ofclaim 11, wherein the dielectric layer includes one or more selectedfrom the group consisting of BaTiO₃, (Ba_(1-x)Ca_(x))(Ti_(1-y)Ca_(y))O₃(where 0≤x≤0.3, 0≤y≤0.1), (Ba_(1-x)Ca_(x))(Ti_(1-y)Zr_(y))O₃ (where0≤x≤0.3, 0≤y≤0.5), Ba(Ti_(1-y)Zr_(y))O₃ (where 0≤y≤0.5), or(Ba_(1-x)Ca_(x)) (Ti_(1-y)Sn_(y))O₃ (where 0≤x≤0.3, 0≤y≤0.1).